To analyze the interference effects on the oscillation of four-probe resistance of one-dimensional nanostructures in experiments, we performed numerical simulation of a nanoscale four-probe system consisting of monatomic carbon chains using self-consistent charge density-functional tight-binding method and nonequilibrium Green's function method. We constructed spectra of the peak spacing of calculated four-probe resistance spectra, and compared them with those expected from a simple model of interference due to multiple reflections between sample-probe contacts. From the peak spacing spectra, the interference effects caused by the multiple reflections and by resonant scattering at the sample-probe contacts are extracted separately. This result suggests that the peak spacing analysis is a potential tool to understand four-probe resistance measurements.